Why are they necessary?
Where are they used?
Why are we concerned with PFAS, instead of other common contaminants like lead?

Polyfluoroalkyl substances (PFAS) are a large family of man-made
chemicals. They share in common the fact that all chemical compounds in
this family incorporate several atoms of the element fluorine. PFAS are
sometimes called PFCs (per- or poly-fluorinated compounds). You might also
see specific compounds referred to (e.g., PFOA, PFOS). Two of the chemical
compounds in the PFAS family that were the most commonly used and produced
are PFOA
(also referred to as C8)
and PFOS.

Here, we'll use the term PFAS (plural, PFAS) to refer to the larger group
of chemicals, unless we are specifically referring to PFOA or PFOS.

PFAS are (or have been) used to make consumer goods resistant to water,
grease, or stains, in products like Gore-Tex rain gear, Teflon no-stick
cookware, and Scotchguard stain-repellent for carpets or furniture
fabric. PFAS are also found in foams used by firefighters to extinguish
oil and gas fires.
→ REFERENCE
BU SPH, PFAS Factsheet
→ REFERENCE
The New Lead - Perfluorinated Compounds (PFCs)

See also:How can I tell whether my water has been contaminted?—see #WATERHow can I tell whether there are PFAS in my body?—see #BLOOD

PFAS are now found almost everywhere in our environment, and it is
difficult to quantify how much people are exposed to and exactly how they
are exposured. For most people in the USA, who are exposed at so-called
"background," or "average", levels of contamination, the primary source of
exposure is most likely from consuming foods that were wrapped in
PFAS-coated packaging. However, people with higher than average exposure
are most likely drinking water that has been contaminated with PFAS.

Is PFAS contamination ongoing, or has it been stopped?
What are the implications of PFAS contamination for new water sources?

Because PFAS are water soluble, the biggest threat of high exposure is through
drinking water. Until recently, we thought that only a few water supplies were
vulnerable to contamination from large PFAS emissions — for example, the water
systems in Ohio and West Virginia that were contaminated on a very large scale by DuPont's
Parkersburg, WV facility.

Today, we're finding that many sources can contribute to PFAS in lakes, rivers, or
underground aquifers. In some areas, the largest source is when firefighting
chemicals, which often contain PFAS, are allowed to run off onto the ground or into
a stream. This may not sound like a major source, but firefighter training can use
huge volumes of these substances over and over at the same spot — a training
facility or an airport, for example. These PFAS-containing foams can then leach
into water supplies, contaminating them.

Since PFAS are used for many purposes, there are other, usually smaller, sources.
For example, clothes treated with PFAS will leech more PFAS out into the sewer --
and possibly into the groundwater — with every laundry cycle. (Breathable
water-proof or water-resistant fabrics are most often treated with PFAS.)

PFAS chemicals are very persistent in the environment, and won't easily break down.
This means that once contamination has occurred, the water supply will likely be
contaminated for many years to come.

PFOA and PFOS, historically the two most important PFAS chemicals, are no longer made in
the USA. However, there are a great many related compounds with similar properties,
which may be use Furthermore, stocks of PFAS firefighting foams can be stored for
decades, and are likely to be used in firefighting training long into the future,
providing future sources of contamination.

How strong is the scientific link between exposure to PFAS and health outcomes?
Where do PFOAs accumulate in the body?
Why do PFAS show up in some people more than others?

We know that most people living in the US are exposed to at least some
level of PFAS chemicals—and many of us are highly exposed. (See #exposed.)
But what are the effects of those chemicals on people?

As is the case with many other "emerging contaminants," PFAS have been in
use for a long time—many decades, in the case of PFOA and PFOS—but we
are only now learning about their health effects. This problem of "using
before understanding" occurs regularly because the US does not require
testing of most new chemicals before they are used commercially. (For more
on the problem of regulating emerging contaminants, see #future.)

The federal Agency For Toxic Substances and Disease
Registry lists these health effects as potentially being associated with
PFAS exposure in humans:
→ REFERENCE
Agency For Toxic Substances and Disease Registry, Health Effects of PFAS

Not all of these effects will necessarily lead to
disease; changes in liver enzymes may never lead to a liver disease, for
example. So there is still uncertainty regarding the significance of some of these
changes. However, other effects (e.g., cancers) represent clearer risks.
It's also important to note that not everyone is equally susceptible to these
effects. For example, developing fetuses and children are much more susceptible
to the endocrine disrupting effects on the thyroid, the
brain, and the immune system, since those hormonal systems are still being
formed and are especially sensitive during development.

PFAS is a large class of chemicals that includes many related compounds.
Only PFOA and PFAS
have been even moderately well studied thus far.

We are really just getting started learning about the effects of PFAS.
In fact, we know there are specific PFAS chemicals already in widespread
use that scientists haven't even
identified, never mind studied.
This is a serious problem with our chemical regulatory system: See #future.

Although PFAS have been in use for decades—and although public health
scientists have expressed concerns about them for many years—they have
been essentially unregulated until recently.

The US regulatory system does not generally require any testing before new chemicals can be used.
Furthermore, in most cases, chemicals cannot be regulated
until they are proven to be toxic.

The presence of several large contamination incidents has now created
enough public awareness that manufacturers have now voluntarily stopped making the most
heavily-used PFAS chemicals. (These chemicals may still be used abroad, however,
and these products are still imported to US.)
Unfortunately, in most cases, we don't yet know what chemicals are being used to replace them,
althought it is very likely that most of the replacements
are also PFAS chemicals.

This demonstrates a serious imbalance between government and industry:
Manufacturers can change their products at will, but EPA is required to
accumulate many years of scientific evidence before regulating a new
chemical.

As one scientist recently pointed out,
we know that there are PFAS being used out there that we haven't even yet
identified!

In November 2016, EPA issued a health advisory for PFOA and PFOS, setting
guidance for permissible limits of these chemicals in drinking water.
→ REFERENCE
US EPA, Drinking Water Health Advisories for PFOA and PFOS

See #safe for details.
For more about regulating chemicals like PFAS, see #future

Testing water for PFAS contamination is possible, although
because PFAS chemicals are so widespread, even collecting a
sample to be tested can be a difficult process.
While costs vary widely, a test for PFAS in water will cost several hundred dollars.

US EPA Method 537
→ REFERENCE
US EPA, Determination of Selected Perfluorinated Alkyl Acids in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
specifies the collection and testing process in great
detail, and this process should be followed if results will be used in any
official or legal process. While Method 537 provides information on
testing for a number of PFAS, it does not test for all of them. Some
test facilities may report only PFOA, or PFOA and PFOS, or another limited
set of PFAS.

The good news is that, if you are on a public water system, your system
managers are responsible for this testing. They may already have test
results, or may be able to get them.

If you receive water from a public supply, your water utility is required to
provide you with an annual Consumer Confidence Report describing what tests have
been performed, and explaining any cases in which the water failed federal water
quality requirements. You can find your Consumer Confidence Report
through the EPA's search
tool, or just try searching for your town's name and the phrase "water quality report"
or similar keywords.
Check your water system's CCR to find out what levels were measured in your local
system, and when and where.

If you're on a well, ask your regular water testing service about
testing for PFAS. Be sure to follow up with your local and state
departments of health and environment to make sure they are aware of your
concerns. In some cases, they may be able to connect you with other
resources. If your groundwater is contaminated, it is likely that the
whole aquifer—the underground body of water your well draws from—is
also contaminated; so it is important that others know about your results.

For details on how to interpret test results, see #interpretFor the question of what level of PFAS contamation is "safe", see #safeFor information about treating water and reducing your PFAS exposure, see #reduce

Testing for PFAS in blood is difficult and expensive, and can only be done
by a small number of laboratories.

Before testing for PFAS in blood, it may be more useful to identify the sources
of the PFAS—for example, by determining whether your drinking water is
contaminated. If that's the case, you'll have better information about how you
were exposed, and how you can reduce your exposure.

Unfortunately, if you have elevated levels of PFAS in your blood, there is
nothing that can be done to remove the PFAS. The best thing you can do is to
identify the source of your exposure, and prevent further exposure.

My test showed that I have PFAS in my blood. How should I interpret this result?

The extremely widespread use of PFAS means that almost all Americans now
have PFAS in their bodies and in their blood. As
test methods become more sensitive, we are able to find PFAS at lower and
lower levels. Currently, about 99% of Americans tested have detectable
levels of PFAS in their blood. Remember, a detectable level of PFAS does
not indicate a specific health concern or health risk.

The US federal government's National Health and Nutrition Examination Survey
(NHANES) provides a great deal of data on PFAS levels in blood, so anyone can
compare their specific results with results from others. This will give you a
sense for whether your specific PFAS exposure is high, or medium, or at the
"background" level of average everyday exposure. We will discuss this data
at #compare
below.

Comparing to other people is useful in giving your context about whether your
exposure is high or low, in comparison with other who have been tested. But we
don't know enough about PFAS to connect any amount in blood with specific health
problems, so the blood test itself won't tell you about any specific health
concerns that may relate to PFAS exposure now or in the future. Some people
might have relatively high amounts of PFAS in their blood, but not have health
effects from PFAS, while others might be more susceptible. For example,
developing children and fetuses are more susceptible to the endocrine disrupting
effects on the thyroid, the brain, or the immune system, since those hormonal
systems are still being formed and are especially sensitive. Unfortunately, kids
also tend to have higher levels of PFAS exposure than adults do. This might be
due to higher exposures (for example, if a kid's diet has more PFAS in packaging
materials), or it might be biological (for example, if kids don't metabolize and
excrete PFAS as well as adults).

The best thing you can do is to reduce any continued exposure to yourself, your
family, and your community. Also, let's try to fix our broken chemical
regulatory system so that this problem doesn't happen again. See #future.

Much more detail about the terminology used in interpreting your results is
available in the longer answer to this question.

When we talk about "safe levels" of exposure, it is critical to distinguish
between blood levels and
drinking water levels. Someone with a "safe" level
of PFAS in their water might still have high levels of PFAS in their blood. In
fact, the scientific data indicates that most Americans get the majority of their
PFAS exposure from sources other than drinking water.

Unfortunately, we simply don't know enough about the toxicity of PFAS to
determine whether a certain amount of PFAS in blood is "safe". The best you
can do with blood results is to compare them with others' to see if yours are
elevated—see #interpret
for more information.

If you receive water from a public supply, your water utility is required to
provide you with an annual Consumer Confidence Report describing what tests have
been performed, and explaining any cases in which the water failed federal water
quality requirements. You can most often find your Consumer Confidence Report
online—try searching for your town's name and the phrase "water quality report"
or similar keywords.

In November 2016, EPA issued a health advisory for PFOA and PFOS.
For more information about this health advisory, see the longer answer to
this question.

After decades of production and use, about 99% of Americans tested now
have detectable levels of PFAS in their blood. Remember, a detectable
level of PFAS does not indicate a specific health concern or health risk.

REDUCING YOUR PFAS LEVELS

The body will naturally metabolize and excrete PFAS over time. However,
this is a very slow process: It is estimated to take 2-4 years to eliminate
half of the PFOA from the body.
There is no proven way to speed up this elimination of PFAS chemicals from the body.
"Toxic eliminating" diets or supplements are not likely to have any effect
on PFAS levels.

The persistence of PFAS is one reason
why preventing future exposure is so important.
For details about how to lower your exposure to PFAS in drinking water,
see the longer answer to this question.

Do commercial filters (e.g. Brita) work for PFAS and other emerging contaminants?
Does boiling water help eliminate PFAS?
Is distilled water safe from PFAS?
Is bottled water safe from PFOA?

Contaminated water can be treated at home by water filters only if they
are specifically designed to remove PFAS. Most commercial water filters
are not.

(DO WE HAVE RECOMMENDATIONS FOR FILTERS?)

Many people see bottled water as a solution—and in cases
where the water system is known to be contaminated, it may be necessary.
However, bottled water is very poorly regulated. In addition, the
environmental footprint of transporting bottled water, and of bottle
waste—almost always plastic—is very high. In cases where PFAS
contamination can be treated at the source, drinking clear tap
water, perhaps
treated with a simple activated carbon filter, is usually the most
environmentally sound and healthiest approach.

Boiling water is useful to kill living parasites—
including bacteria and viruses—in contaminated drinking water. However,
this approach isn't effective with most toxics. PFAS is quite stable and
persistent, and boiling water is unlikely to remove any significant amount of
it.

While filtration may be useful, the best approach for significantly
contaminated water will be to make sure your water supplier manages
contamination of the aquifer at the source. See #reduce
and #water for more information.

If you know or suspect that your community's water has been contaminated with
PFAS, a good starting place is to get your #water
tested.
Be sure to check the #CCR
published by your water supplier for information on what testing they've already
done.
If your water supply is not testing for PFAS, pressure your local government to have
the water tested.
If your water is contaminated, be sure your state and local health officials know
about the problem. If the contamination is below the EPA's #advisory,
they may not be willing (or required) to act. However, check guidance from other
states and localities to see if you exceed guidelines set elsewhere.

It's important to identify the source of
contamination. Are there major
sources—for example, heavy use of fire-fighting foams—in your area?
If the source is not already known, your state and local health officials may be
able to help you track it down.
If your water is contaminated,
you may want to have your #blood
tested as well. Remember, testing—especially blood testing—is expensive.
Talk to your state and local officials about setting up a monitoring program.

Get organized!

You can't respond to contamination alone—you'll need the help of your neighbors
and friends, as well as scientists and government officials.
You need to organize!
A number of resources exist to help your community get organized to fight
pollution. If you know of groups in your area, contact them and ask for help.
You can always contact
Toxics Action Center for
connections and next steps.

In addition to organizing help, you may need expert assistance to help your
community understand their contamination, the possible effects, and the best ways to
respond. Consider contacting local colleges and universities (especially
schools of public health) for assistance.
Toxics Action Center, and other
that focus on community health and environmental justice, should also be able to
connect you with scientists who can help.

Is a health study right for your community?

Many communities immediately decide that they need the state to perform a health
study of their community to evaluate the effect of the pollution. While a health
study can provide important information, it might also prove inconclusive, and in
either case it is likely to take a substantial investment of time and resources.

If you've done the basic background work above, and you think that a health study is
the right next step, see our guide, Is a Health Study Right
for Your Community?. This guide will help you establish your research
question and develop the best study to answer your community's questions.

How can we make sure contamination like this doesn't happen in the future?

What can we do to promote responsible chemical use & development?
How can chemists find safer chemicals?
Are the C6 chemicals good replacements for the C8 PFAS chemicals

The current situation—in which millions of Americans are exposed to
PFOA, PFOS, and probably to other PFAS in their drinking water—should never have happened.
→ REFERENCE
'Unsafe levels of toxic chemicals found in drinking water for six million Americans'

It happened because we allowed a chemical to be used widely and at high
volumes before we had adequately tested it.
This is not an isolated incident or a one-time occurance.
The same thing happened with leaded gasoline, and with lead in paint. The
same thing happened with flame retardants and with bisphenol A. Incidents
like these, and many more, happen because of the design of the US
regulatory system, which over the past 40 years has not required companies
to test chemicals before using them.
(This situation may now be changing; see below for information on changes
to federal
regulations.)

By contrast, European chemicals regulation requires extensive testing for
human and environmental health effects before a chemical can be placed on
the market—summed up in the simple phrase, "no data, no market".

The difference between these two systems lies in who has the burden of
proof. In Europe, a chemical manufacturer must prove a chemical safe
before it is used. In the US, the government must prove that a chemical
is harmful before its use can be stopped.